WASHINGTON — The White House refused Thursday to say whether it secretly fed intelligence reports to a top Republican lawmaker, fueling concerns about political interference in the investigation into possible coordination between Russia and the 2016 Trump campaign.

Fending off the growing criticism, the administration invited lawmakers from both parties to view classified material it said relates to surveillance of the president’s associates. The invitation came as The New York Times reported that two White House officials secretly helped House intelligence Committee Chairman Devin Nunes examine intelligence information last week.

Nunes is leading one of three investigations into Russia’s attempt to influence the campaign and Trump associates’ possible involvement.

Late Thursday, an attorney for Michael Flynn, Trump’s ex-national security adviser, said Flynn is in discussions with the intelligence committees about speaking to them in exchange for immunity.

Other Trump associates have volunteered to speak with investigators, but have not publicly raised the issue of immunity.

The House panel’s work has been deeply undermined by Nunes’ apparent coordination with the White House. He told reporters last week that he had seen troubling information about the improper distribution of Trump associates’ intercepted communications, and he briefed the president on the material, all before informing Rep. Adam Schiff, the committee’s top Democrat.

Speaking on Capitol Hill Thursday, Schiff said he was “more than willing” to accept the White House offer to view new information. But he raised concerns that Trump officials may have used Nunes to “launder information to our committee to avoid the true source.”

“The White House has a lot of questions to answer,” he declared.